1. Field of the Invention
The invention relates to an optical instrument assembly, and in particular, to a zoom lens assembly and a zoom lens module.
2. Description of the Related Art
As shown in FIGS. 1 and 2, a focusing device 10 often assembled on an optical image device (for example, a camera and a projector) has functions of zooming and focusing. The focusing device 10 has a first frame set 11 along an axis I, a second frame set 12, a fixing tube 13 sheathing the first frame set 11 and the second frame set 12, a first cam tube 14 and a second cam tube 15 sheathing the fixing tube 13, three first driving bolts 16 and three second driving bolts 17.
The first frame set 11 has a through space 111 along the axis I to receive a first lens group (not shown), and three tap holes 112 disposed radially at intervals of equal angle.
The second frame set 12 has a through space 121 along the axis I to receive a second lens group (not shown), and three tap holes 122 disposed radially at intervals of equal angle.
The fixing tube 13 has three first guiding notches 131 disposed along the axis I aligning to the tap holes 112, and three second guiding notches 132 disposed along the axis I aligning to the tap holes 122.
The first cam tube 14 has three cam grooves 141 corresponding to the tap holes 112.
The second cam tube 15 has three cam groove 151 corresponding to the tap holes 122.
The first driving bolts 16 respectively pass through the cam grooves 141, the first guiding notches 131 and then screws into the radial tap holes 112.
The second driving bolts 17 respectively pass through the cam grooves 151, the second guiding notches 132 and then screws into the radial tap holes 122.
For adjustment, the first cam tube 14 is rotated, so that the cam grooves 141 drive the first driving bolts 16 to move in the first guiding grooves 131, further moving the first frame set 11 close to or away from the second frame set 12 along the axis I. Relatively, the distance between the first lens group and the second lens group can be changed to achieve zooming purposes.
Moreover, rotating the second cam tube 15 to drive the second frame set 12 to move along the axis I also achieves zooming purposes.
Although the focusing device 10 comprises the above functions, the following disadvantages still exist.
First, the focusing device 10 requires many components which increases the manufacturing costs.
Second, since the first frame set 11 is necessary to receive the first lens group and the second frame 12 is necessary to receive the second lens group, more radial space is necessary, the size of the focusing device 10 is relatively large